High Quality Diamond Drill Bits with Economical, Fast Cutting Surface - Made of high strength nickel plated carbon steel makes these drill bits durable and precise; The bit head tip is made of 80 grit diamond coating, which is uniform; It helps a lot to increase the drilling speed and sharper than other ordinary saws. 10pcs Mainly Used Sizd - Contains the following diameters: 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 50mm; Using laser marking, the size will satisfy most of your different needs. Application - Suitable for use in a hole drilled on glass, marble, tile, block jars, fiberglass, porcelain and ceramic tile, slate BLVA0299, granite light stone, etc. It works with all electric drill and impact drill. Nice design - the center holes and side holes help to easily remove the waste material; and the nickel plated surface, prolong the service life, improve the surface corrosion resistance Notice type - When cutting hard materials, it is important to ensure the cutter is